Data for use in computing systems is stored on various types of media, including magnetic tapes, magnetic disks and optical disks. Rather than manually loading media units into a device capable of reading and recording the data located on the media, automated storage libraries have been developed. Such libraries employ open faced receptacle columns each having a plurality of storage compartments for passively storing the cartridges holding the media. Associated with the receptacle columns, is a picker mechanism which can remove a media unit from its location within the storage compartment and move it to a disk drive which can record or read data. After the recording or reading process within the drive unit, the media unit is moved by the picker mechanism back to the storage compartment.
It is an object of the present invention to provide a storage system capable of storing large quantities of magnetic or optical disk media within a given storage space. It is another object to provide an optical sensing system within each receptacle column to interact with specifically designed media units to derive various information therefrom.